The delivery of Endeavor to California marks the end of a career. Not Endeavor's, but NASA's Shuttle Carrier Aircraft 905. In just a few weeks, she will mark the 42nd anniversary of her first flight, by which time she may have made her final flight.
The Boeing 747 (model 747-123) was constructed at Boeing's Everett, Washington plant. All their planes carry a construction number an line number (often written as 20107/86 for this plane). She was built for American Airlines and carried the registration number N9668. Her career with American Airlines was brief, less than four years, before she was sold to NASA. From 1974 to 1977 she was modified to carry the space shuttles. Inside, she was gutted down to her framework, except in the bow where she still has her original spiral staircase and the forward first class seating.
In 1977 she got to work. Her career with NASA started with Enterprise. The flights included five very important drop tests. To do this, 905 (as I'll call her from here out) dropped out from below the shuttle and then the shuttle flew (if you can call it that) to the landing strip at Edwards Air Force Base. The first drop test was with the engine covering, but the important tests were the ones with the [fake] engines exposed, just as her sisters would do when landing after their missions.
This was the beginning of a close associate between 905 and Enterprise. Before Columbia had ever rolled out, Enterprise had been hauled around and been processed just like it was a flight worthy orbiter. 905 delivered both Columbia and Challenger to Florida and retrieved the various orbiters from the landing strips they used besides at KSC.
With a fleet of 4 operational orbiters, NASA purchases a second 747 (a 747-200 SP) registered as N911NA, or just 911, to do half the work. 911 flew for the last time earlier in 2012. It has fallen to 905 to deliver Discovery, Enterprise, and now Endeavor to their new homes. That job is now done and it is time for her to retire. She first flew on October 15, 1970 and is about to make her last flight almost exactly 42 years later.
Goodbye 905. Thanks for your service. You will be missed as will your 6 most notable passengers.